Reclamation of metal from scrap

Abstract

A process for recovering metal from scrap using a furnace having a bath chamber, a dry hearth chamber, an exhaust duct, and an incinerator for burning fumes from the dry hearth chamber is presented. The process includes conveying oxygen or oxygen enriched air to the incinerator in order to produce a desired oxygen concentration within the incinerator; introducing at least a major portion of the gases leaving the incinerator into the bath chamber; venting a minor portion of the gases from the bath chamber through the exhaust duct; and passing at least a major portion of the balance of the gases through the dry hearth chamber and recycling the balance of the gases to the incinerator, and wherein the concentration of oxygen present in one of the furnace and a duct which conveys hot combustion gases from the incinerator to the furnace is determined, and the volume of oxygen admitted to the incinerator is controlled in order to maintain the desired oxygen concentration within the incinerator.

I claim: 
     
       1. A process for recovering metal from scrap using a furnace having a bath chamber, a dry hearth chamber, an exhaust duct, and an incinerator for burning fumes from said dry hearth chamber, wherein said process comprises (a) conveying oxygen or oxygen enriched air to said incinerator in order to produce a desired oxygen concentration within said incinerator; (b) introducing at least a major portion of the gases leaving said incinerator into said bath chamber; (c) venting a minor portion of the gases from said bath chamber through said exhaust duct; and (d) passing at least a major portion of the balance of said gases through said dry hearth chamber and recycling said balance of said gases to said incinerator, and wherein the concentration of oxygen present in one of said furnace and a duct which conveys hot combustion gases from the incinerator to the furnace is determined, and the volume of oxygen admitted to said incinerator is controlled responsive to the concentration of oxygen determined in order to maintain said desired oxygen concentration within incinerator. 
     
     
       2. The process of claim 1, wherein all the gases leaving said incinerator are introduced into said bath chamber. 
     
     
       3. The process of claim 2, wherein said fumes are blown by a fan from said dry hearth chamber into said incinerator. 
     
     
       4. The process of claim 1, wherein all the balance of the gases leaving said bath chamber are passed through said dry hearth chamber. 
     
     
       5. The process of claim 1, wherein said exhaust duct is provided in said bath chamber. 
     
     
       6. The process of claim 5, wherein said exhaust duct is provided at the downstream end of said bath chamber. 
     
     
       7. The process of claim 1, wherein said incinerator is the sole or main source of heat for the furnace. 
     
     
       8. A process for recovering metal from scrap using a furnace having a bath chamber, a dry hearth chamber, an exhaust duct, and an incinerator for burning fumes from said dry hearth chamber, wherein said process comprises (a) conveying oxygen or oxygen enriched air to said incinerator in order to produce a desired oxygen concentration within said incinerator; (b) introducing at least a major portion of the gases leaving said incinerator into said bath chamber; (c) venting a minor portion of the gases from said bath chamber through said exhaust duct; and (d) passing at least a major portion of the balance of said gases through said dry hearth chamber and recycling said balance of said gases to said incinerator, and wherein the temperature of liquid metal in said bath chamber is detected, and the volume of oxygen admitted to said incinerator is controlled responsive to the temperature detected in order to maintain said desired oxygen concentration within said incinerator. 
     
     
       9. The process of claim 8, wherein the concentration of oxygen present in said bath chamber is determined and the volume of fuel admitted to said incinerator is controlled responsive to said concentration of oxygen determined. 
     
     
       10. The process of claim 8, wherein all the gases leaving said incinerator are introduced into said bath chamber. 
     
     
       11. The process of claim 10, wherein said fumes are blown by a fan from said dry hearth chamber into said incinerator. 
     
     
       12. The process of claim 8, wherein all the balance of the gases leaving said bath chamber are passed through said dry hearth chamber. 
     
     
       13. The process of claim 8, wherein said exhaust duct is provided in said bath chamber. 
     
     
       14. The process of claim 13, wherein said exhaust duct is provided at the downstream end of said bath chamber. 
     
     
       15. The process of claim 8, wherein said incinerator is the sole or main source of heat for the furnace.